High altitude, boiling points

Dibutyl ether is an alternative to diethyl ether when a high reaction temperature is required it has also been found useful by laboratories in the tropics or at high altitude, where the low boiling point of diethyl ether is a problem. Diisopropyl ether has also been used, but is notorious for its tendency to form peroxides. 

Table A-2 Boiling and freezing point properties 843 Table A-3 Properties of solid metals 844 846 Table A-4 Properties of solid nonmetals 847 Table A-5 Properties of building materials 848-849 Table A-6 Properties of insulating materials 850 Table A-] Properties of common foods 851-852 Table A-8 Properties of miscellaneous materials 853 TableA-9 Properties of saturated water 854 Table A 10 Properties of saturated refrigerant-134a 855 Table A-11 Properties of saturated ammonia 856 Table A-12 "Properties of saturated propane 857 Table A-13 Properties of liquids 858 Table A-14 Properties of liquid metals 859 Table A- 5 Properties of air at 1 atm pressure 860 TableA-16 Properties of gases at 1 atm pressure 861-862 Table A-17 Properties of the atmosphere at high altitude 863 Table A-18 Emissivities of surfaces 864-865 Table A-19 Solar radiative properties of materials 866 Figure A-20 The Moody chart for friction factor for fully developed flow in circular pipes 867...

It follows from the definition that the boiling point of a liquid is not constant. It depends on the atmospheric pressure. At high altitudes, where the atmospheric pressure is low, the boiling point of a liquid, such as water, is lower than the normal boiling point (for water, 100°C). High atmospheric pressure increases the boiling point. 

Jet planes flying at high altitudes require kerosene with solidifying points below — 50° C. Biological de-waxing of a distillate having a boiling point between 170° C and 200° C can induce the required property with the simultaneous production of nutrient protein. 

At higher altitudes, the hoUtng points of hquids are lower because there is a lower atmospheric pressme above the hq-uid. The temperature at which food cooks is determined hy the temperature to which the water in the food can he heated before it escapes as steam. Thus, food cooks at a lower temperature at high elevations where the boiling point of water is lowered. 

The effect of pressure on boiling point also explains why it takes longer to cook food at high elevations than it does at sea level. The atmospheric pressure is lower at higher altitudes, so water boils at a temperature lower than 100 C, and foods generally take longer to cook. 

The following demonstration shows one of the properties of a solution, called colligative properties, which can be observed when a nonvolatile compound dissolves in a solvent, such as water. The normal boiling point of water under standard atmospheric pressure (1 atmosphere [a unit of pressure]) is 100°C. At high altitudes, the atmospheric pressure is lower, and the boiling point is lower. Let us say that we perform the experiment at standard pressure (although in Jemsalem, where the demonstrator lives, the pressure is lower, and the boiling temperature is also lower). 

Why do you think people who live at high altitudes are advised to add salt to water when boiling food like pasta What mole fraction of NaCI is needed to raise the boiling point of HjO by 3 C Does the amount of salt added to water (typically about one teaspoon to four quarts of water) substantially change the boiling point (HjO) = O.srC/molal. 

At high altitudes, where atmospheric pressures are lower than 760 mmHg, the boiling point of water is lower than 100 °C. For example, a typical atmospheric pressure in Denver is 630 mmHg. This means that water in Denver boils when the vapor pressure is 630 mmHg. From Table 11.5, we see that water has a vapor pressure of 630 mmHg at 95 °C, which means that water boils at 95 °C in Denver. 

---